3cx volume control

I am from Brazil and I have a little poblem about the 3cx,
I am using the usb heardphone and some clients are give me a feedback saying that the transmission and reception ( TX and RX ) is low, I am using a C-Midia chip in this hearphone.
I would like to know if have some update or configuration to solve this problem,
someway to control the level of the volume in 3cx Phone.
You guys can give me a answer here, or if you prefer here is my e-mal
adrianotlk@gmail.com